Quantitative transmission/emission detector system and methods of detecting concealed radiation sources

Abstract

Apparatus and methods for screening inanimate objects for detecting concealed radioactive substances. The apparatus and method use a combination of at least one gamma-emission detector and the generation of a transmission image to non-invasively evaluate the contents of an inanimate object, such as a container, in order to determine the presence of absence of a radioactive substance. A variety of configurations of gamma-emission detectors and transmission detectors may be used to rapidly scan objects for the presence or absence of a radioactive substance.

1. An apparatus for detecting radioactive material within an inanimate object, said apparatus comprising at least one gamma-emission detector and transmission imaging means, said detector operating in conjunction with said transmission imaging means to determine the presence or absence of the radioactive material in the inanimate object, said transmission imaging means being adapted to assess gamma ray attenuation characteristics within the inanimate object wherein said gamma-emission detector determines the presence of radioactive material based upon said assessment of said gamma ray attenuation characteristics wherein said transmission imaging means is arranged to detect the presence of the radioactive substance in the inanimate object by first creating a transmission image of the internal portions of the object, said gamma-emission detector being arranged to evaluate gamma emissions from the object by scanning the object at a rate based on the transmission image created. 
   
   
     2. The apparatus of  claim 1  wherein said at least one gamma-emission detector comprises at least one primary gamma-emission detector and said at least one gamma-emission detector comprises at least one secondary gamma-emission detector, said at least one primary gamma-emission detector operating at a single scan speed, said at least one secondary gamma-emission detector operating at a speed determined through attenuation analysis of discrete areas identified in the transmission image as having high attenuation profiles. 
   
   
     3. The apparatus of  claim 2  further comprising neutron interrogation of the inanimate object in conjunction with said gamma ray attenuation characteristics, said neutron interrogation being applied to portions of the inanimate object having high attenuation profiles prior to the operation of said at least one secondary gamma-emission detector. 
   
   
     4. An apparatus for detecting radioactive material within an inanimate object, said apparatus comprising at least one gamma-emission detector and transmission imaging means, said gamma-emission detector being arranged to detect gamma emissions from the inanimate object, said transmission imaging means being arranged to assess gamma emission attenuation characteristics of the inanimate object; said apparatus further comprising means for making an automatic determination if said gamma emission was sufficient to detect the presence or absence of the radioactive material in the inanimate object based on said assessment of gamma emission attenuation characteristics; wherein said at least one gamma-emission detector automatically scans areas of the inanimate object identified as having a high attenuation profile during the transmission imaging at scan rates based on said assessment of gamma emission attenuation characteristics, said apparatus further comprising means for neutron interrogation of the entire inanimate object. 
   
   
     5. A method for detecting the presence of radioactive material in an inanimate object comprising
 a. creating a transmission image of the internal portions of the inanimate object; 
 b. assessing gamma emission attenuation characteristics of said inanimate object based upon said transmission image; 
 c. evaluating gamma emissions from the inanimate object based on said assessment of gamma emission attenuation characteristics, to determine the presence or absence of the radioactive material in the inanimate object; wherein said evaluation of the gamma emissions is accomplished at a constant speed; and 
 d. providing a secondary gamma-emission scan at a variable speed wherein said variable speed is determined based on said assessment of gamma emission attenuation characteristics. 
 
   
   
     6. A method for detecting the presence of radioactive substances in an inanimate object comprising the steps of
 a. evaluating gamma emissions from the object wherein said evaluation of gamma emissions is accomplished at a constant speed; 
 b. based on said evaluation of gamma emissions, creating a transmission image of the internal portions of the object to determine the whether any areas of the evaluated object require further analysis; and 
 c. providing a secondary gamma-emission scan at a variable speed wherein said variable speed is determined through evaluation of attenuation characteristics of the object based on said transmission image. 
 
   
   
     7. A method for detecting the presence of radioactive substances in an inanimate object comprising
 a. creating a transmission image of the internal portions of the inanimate object; 
 b. assessing gamma ray attenuation characteristics of the inanimate object based on said transmission image; 
 c. interrogating the inanimate object using neutrons; 
 d. evaluating gamma emissions from the object based on said assessment of gamma emission attenuation characteristics wherein said evaluation of gamma emissions is accomplished at a constant speed; and 
 e. providing a secondary gamma-emission scan at a variable speed wherein said variable speed is determined through evaluation of the attenuation characteristics of the object as indicated in the transmission image.